1. Field of the Invention
The present invention generally relates to a motor-driven system. It particularly relates to a motor-driven system for use in a motor-driven golf cart, a motor scooter, an electric automobile, and a robot carrier car; a motor-driven system for use in index table driving, dram driving in a copying machine or the like; and a motor-driven system for use in a game machine and so on.
2. Description of the Related Art
Conventionally, as the electric motor of an electric automobile, a permanent magnet type brushless motor, or a reluctance type brushless motor which does not use any permanent magnet has been used.
Further, as the motor for driving a transfer drum of a copying machine or for driving a drum of a laser beam printer, an inner rotation type electric motor provided with a reduction gear has been used.
In the configuration of such a conventional motor-driven system as described above, however, there were problems as follows.
(1) Since the electric motor had no inductors formed out of magnetic teeth provided at the forward ends of the respective main poles of the stator, the number of the poles of the rotor was small so that the torque at a low speed was small.
(2) In the case of performing direct driving without use of any reduction gear, it was necessary to make the number of the poles of the rotor large, and, at that time, the number of the main poles of the stator (equal to the number of slots) was large, the inner diameter of the stator was large and the motor per se was large in size.
(3) Even in the case of using a reduction gear, if the number of the poles of the rotor was small, the reduction gear ratio was large.
(4) In the case of closed loop driving, there was a problem that the system was expensive and the torque at a low speed was small, because the stator had no inductors and the driving was not of a 3-phase system which was simple in driving and which was large in torque.
It is an object of the present invention to solve the above problems and to provide a motor-driven system having a stator provided with inductors constituted by magnetic teeth at the forward ends of the respective main poles of the stator to thereby realize an optimal driven system for an electric automobile, a robot carrier car, a dram of a copying machine or the like.
In order to achieve the above object, according to a first aspect of the present invention, a rotational electric machine comprises: a stator having an annular magnetic substance, main poles provided so as to extend radially outward from the magnetic substance, windings wound on the main poles respectively, and inductors each constituted by a plurality of magnetic teeth formed at a forward end of corresponding one of the main poles; and an outer rotor type permanent magnet rotor having north (N) and south (S) magnetic poles arranged alternately on an inner circumference of the rotor and in a rotating direction of the rotor, the stator and the rotor being in opposition to each other while an air gap is held therebetween. In the rotational electric machine, a motor-driven system is provided so that an outer rotating body such as a tire, a drum, a table or the like is mounted on an outer circumferential portion or on a side portion of the rotor.
According to a second aspect of the present invention, a rotational electric machine comprises: a stator having an annular magnetic substance, main poles provided so as to extend radially outward from the magnetic substance, windings wound on the main poles respectively, and inductors each constituted by a plurality of magnetic teeth formed at a forward end of corresponding one of the main poles; and an outer rotor type rotor constituted by a magnetic substance having magnetic teeth formed on an inner circumference thereof, the stator and the rotor being in opposition to each other while an air gap is held therebetween. In the rotational electric machine, a motor-driven system is provided so that an outer rotating body such as a tire, a drum, a table or the like is mounted on an outer circumferential portion or on a side portion of the rotor.
According to a third aspect of the present invention, in a rotational electric machine according to the first and second aspects, a motor-driven system wherein an outer rotating body such as a tire, a drum, a table or the like is mounted on the outer circumferential portion or on the side portion of the rotor through an output portion of a reduction gear, the output portion being concentric with a rotation shaft and output of the rotational electric machine.
According to a fourth aspect of the present invention, in a rotational electric machine according to any one of claims the first to third aspects, a motor-driven system is provided so that the stator has a 3-phase winding structure.
According to a fifth aspect of the present invention, as stated in claim 5, in a rotational electric machine according to any one of the first to third aspects, or in a rotational electric machine which is obtained by changing an outer roller type rotational electric machine according to the first or second aspects into an inner rotor type, or in a rotational electric machine of the inner rotor type and of a 3-phase HB type in which the number of rotor teeth is P, a motor-driven system is provided so that, as a voltage to be applied to the rotational electric machine, a voltage of a battery is used while the battery voltage is stepped up/down by chopping, wherein P=m(3nxc2x11) in which m is the number of main poles of the stator for each phase and an integer not smaller than 1, or P=k(6nxc2x11) in which 2 k is the number of main poles of the stator for each phase and each of k and n is an integer not smaller than 1.
According to a sixth aspect of the present invention, in a rotational electric machine according to any one of the first to third aspects, or in a rotational electric machine which is obtained by changing an outer rotor type rotational electric machine according to the first or second aspects into an inner rotor type, or in a rotational electric machine of the inner rotor type and a 3-phase HB type in which the number of rotor teeth is P, a motor-driven system is provided so that a phase of current relative to a motional electromotive force of the rotational electric machine is controlled, and so that P=m(3nxc2x11) in which m is the number of main poles of the stator for each phase and an integer not smaller than 1, or P=k(6nxc2x11) in which 2 k is the number of main poles of the stator for each phase and each of k and n is an integer not smaller than 1.
Further, according to a seventh aspect of the present invention, in a rotational electric machine according to any one of the first to third aspects, or in a rotational electric machine which is obtained by changing an outer rotor type rotational electric machine according to the first or second aspects into an inner rotor type, or in a 3-phase rotational electric machine of an outer or inner rotor type having main poles the number of which is 3 m or 6 k with 3-phase windings, the rotor being of a HB type in which the number of rotor teeth is P or being of a cylindrical type in which the number of rotor poles is 2P and the cylindrical rotor is magnetized into north (N) and south (S) magnetic poles alternately, a motor-driven system is provided so that positional information of the rotor is obtained to thereby obtain timing of excitation of windings, and so that P=m(3nxc2x11) in which m is the number of main poles of the stator for each phase and an integer not smaller than 1, or P=k(6nxc2x11) in which 2 k is the number of main poles of the stator for each phase and each of k and n is an integer not smaller than 1.
According to an eighth aspect of the present invention, in a rotational electric machine according to any one of the first or third aspects, or in a rotational electric machine which is obtained by changing an outer rotor type rotational electric machine according to the first or second aspects into an inner rotor type, or in a 3-phase rotational electric machine of an outer or inner rotor type having main poles the number of which is 3 m or 6 k with 3-phase windings, the rotor being of a HB type in which the number of rotor teeth is P or being of a cylindrical type in which the number of rotor poles is 2P and the cylindrical rotor is magnetized into north (N) and south (S) magnetic poles alternately, a motor-driven system is provided so that the axis of the rotating magnetic field is excited by the 3-phase excitation, microstep excitation or fullstep excitation which is advanced by xcex3 degrees with respect to the shaft of the rotor at a present position. Here, P=m(3nxc2x11) in which m is the number of main poles of the stator for each phase and an integer not smaller than 1, or P=k(6nxc2x11) in which 2 k is the number of main poles of the stator for each phase and each of k and n is an integer not smaller than 1.
According to a ninth aspect of the present invention, a motor-driven system according to the eighth aspect is provided so that the value of xcex3 is equal to 90xc2x0 (xcex3=90xc2x0) in terms of electrical angle.
Further, according to a tenth aspect of the present invention, a motor-driven system according to the eighth aspect is provided so that when the value of xcex3 is in a range of 0 less than xcex3 less than =90xc2x0, the motor is driven as an open loop stepping motor, or when xcex3 greater than 90xc2x0, the motor is driven as a closed loop brushless motor.